While graphic design and pre-press have been digital since the turn of the century, the physics and chemistry of ink on paper for offset printing remains constant, completely unaffected by the shift to digital design. One of my favourite Graphic Art Production books, Production for Graphic Designers (5th Edition) has a very useful entry on what you need to know in order to achieve high quality printing on uncoated stock. I reproduce it here because without this pre-press knowledge producing high-quality jobs successfully on uncoated stock, including colour advertising on newsprint can easily result in bad surprises for all stakeholders in a print job. As the originator of the work it is my responsibility professionally to speak with the printer about who needs to apply the colour profile your print job for the specific press and paper combination it will be running on, and at what stage in production the profiles are to be applied. This succinct reference is an excerpt from my favourite production reference book by Alan Pipes.
High-quality jobs can be successfully printed on uncoated paper stock—if you compensate for dot gain and choose the correct screen ruling. Ink dries partially by absorption, so the dots will spread. As they expand and merge, detail is lost in the shadow areas and the whole image flattens [loses contrast, tonal range, colour saturation ‘action and variability’]. Dot gain is especially critical in the case of textured papers an on darke or warmer-toned papers, and dot-gain compensation might raange from two to three percent in the highlights, to seven to 10 percent in the shadows to “open up” the dots on the film/plate. Waterless plates require less dot-gain compensation because the ink dot sits on the surface rather than being absorbed. The type of stock also dictates the screen ruling.
- Well-formed, ultrasmooth stock can take screens from 150–175lpi;
- lightly textured stock, such as laid and antique, 120—135lpi;
- while for heavily textured, open fibred, and embossed stock, stick to 110—135lpi.
— Production for Graphic Designers (5th Edition) – Alan Pipes